In order to meet the increasing requirements in the mobile communication system, and particularly, in order to meet the requirements of a higher data rate, a lower time delay, an improved system capacity, coverage area and the like, the 3rd Generation Partnership Project (3GPP) organization starts a Long Term Evolution (LTE) project.
In the existing LTE project, physical resources are shared by all users, and the physical resources are allocated and scheduled by a base station. The LTE project involves a Data demodulation (DM) pilot for providing information on uplink channel estimation and uplink coherent demodulation and detection, which is similar to an uplink pilot in an existing 3G system. As described above, in order to allocate and schedule uplink physical resources, for example, in the case that channel conditions are degraded in a frequency band in which a User Equipment transmits data or the frequency band resources are insufficient, the base station is required to adjust the frequency band in which the User Equipment transmits data, in addition to the DM pilot. In view of the above, an uplink Channel Sounding (CS) pilot is further introduced in the LTE project for sounding the uplink channel quality.
For example, a User Equipment may transmit a CS pilot in one or more frequency bands, and after a base station receives the CS pilot from the User Equipment, the base station may estimate the channel quality in the one or more frequency bands according to the CS pilot, to determine a frequency band with a better channel quality within which the User Equipment transmits data. Thus, the uplink frequency band resources may be allocated and scheduled.
A CS pilot may be carried in a subframe of a radio frame. In the LTE project, different frame structures are employed in various duplexing modes. The duplexing modes in the LTE project include a Time Division Duplexing (TDD) mode and a Frequency Division Duplexing (FDD) mode. FIG. 1 shows a diagram of the frame structure used in the TDD mode. As shown in FIG. 1, a radio frame includes two half frames with the same length. The radio frame includes Subframes 0 to 9, where Subframes 1 and 6 include three special time slots, including a Downlink Pilot Time Slot (DwPTS), a Guard Period (GP) and an Uplink Pilot Time Slot (UpPTS). The 8 general subframes may be divided into uplink subframes and downlink subframes. A CS pilot is carried in an uplink subframe. Additionally, it is proposed to employ OFDM technologies in the LTE project at present, and a general subframe of the LTE project includes 14 OFDM symbols.
In the present developing LTE standard, there is no particular solution in which a CS pilot is transmitted in the TDD mode.